The present invention is directed generally to an anastomosis device. More specifically the present invention is directed to an externally directed apparatus for forming an opening in a vessel for subsequent anastomosis.
An anastomosis is an operative union of two hollow or tubular structures. Anastomotic structures can be part of a variety of systems, such as the vascular system, the digestive system or the genitourinary system. For example, blood is shunted from an artery to a vein in an arteriovenous anastomosis, and from the right pulmonary artery to the superior vena cava in a cavopulmonary anastomosis. In other examples, afferent and efferent loops of jejunum are joined in a Braun""s anastomosis after gastroenteroscopy; the ureter and the Fallopian tube are joined in a ureterotubal anastomosis, and the ureter and a segment of the sigmoid colon are joined in a ureterosigmoid anastomosis. In microvascular anastomosis, very small blood vessels are anastomosed usually under surgical microscope.
The operative union of two hollow or tubular structures requires that the anastomosis be tight with respect to the flow of matter through such structures and also that the anastomosed structures remain patent for allowing an uninterrupted flow of matter therethrough. For example, anastomosed blood vessels should not leak at the anastomosis site, the anastomotic devices should not significantly disrupt the flow of blood, and the anastomosis itself should not cause a biological reaction that could lead to an obstruction of the anastomosed blood vessels.
In particular, anastomosed blood vessels should ideally not develop hyperplasia, thrombosis, spasms or arteriosclerosis. Because anastomosed structures are composed of tissues that are susceptible to damage, the anastomosis should furthermore not be significantly detrimental to the integrity of these tissues. For example, injury to endothelial tissue and exposure of subintimal connective tissue should be minimized or even eliminated in vascular anastomosis. Anastomosis techniques generally intend to provide leak-proof joints that are not susceptible to mechanical failure, and they also intend to minimize damage and reduce the undesirable effects of certain operational features that may lead to post-anastomosis complications.
Optimal anastomosis requires a clean, complete opening in a vessel with minimal dangling threads of tissue. Conventional cutting techniques involve the external positioning of an anvil into the lumen of a vessel that is smaller than the cutter so that the vessel is cut as the cutter passes over the anvil. Such conventional cutting techniques operate much like a typical hand held paper punch used for forming holes by pushing a cutter over an anvil. Just like paper punches, such vascular punches often fail to fully make the cut and leave a portion attached, creating a xe2x80x9cdangling chadxe2x80x9d effect. The connective tissue in blood vessels in combination with the moist condition of the blood vessels further limits the effectiveness of such prior art cutting techniques. More particularly, cutting a moist highly interconnected material by squeezing it between the anvil and the cutter often results in part of the tissue merely slipping between the anvil and the cutter such that a portion is still attached. Based on the foregoing, there is a need in the art for improved methods, apparatus and systems for forming openings in vessels.
An object of the present invention is to provide an externally directed anastomosis fenestra cutting apparatus for consistently forming openings for subsequent anastomosis.
A further object of the invention is to provide a cutting device that can be reliably used to consistently form clean cuts in a vessel wall.
Still another object of the invention is to provide a device that is versatile enough to be suitably combined with a variety of vascular anastomosis techniques.
The cutting apparatus of the present invention includes an anvil, an anvil pull and a cutter. The anvil is inserted through a small incision at the anastomosis site and brought into contact with the interior wall of a vessel so that the anvil distends the wall of the vessel. The cutter is then urged against the portion of the vessel wall that is distended by the anvil to form an opening in the vessel wall.
The cutting apparatus consistently creates a complete cut having a perimeter with a desired shape such as a circle or an ellipse depending on the type of anastomosis. The precision of the cutting is due to several features. The vessel wall is distended over the anvil which enables the wall to be stretched. This assists in creating a clean cut.
The anvil is larger than the cutter so that the cut is formed due to the pressure between anvil and the cutter instead of forcing the vessel between the cutter and the anvil. The anvil has an engaging end that is preferably convex and spherical so that when engaged by a cylindrical cutter the cutter can cut against the anvil at any position in which the cutting edge is initially set against the engaging end. The cutter is also preferably spring biased which provides increased pressure for engaging the anvil.
In one embodiment, the anvil is made of a material that is softer than the material from which the cutter is made. The softer material of the anvil enables the cutter to cut into the anvil while cutting an opening into a vessel. By cutting into the anvil while cutting the vessel, the cutter is able to provide a clean cut. Alternatively, the anvil may be made of a material that is more flexible than the cutter and enables the cutter to depress the surface of the anvil inwardly when a vessel is cut. Also the anvil and cutter may be formed from materials with about the same hardness or from the same materials.
Also, the anvil is preferably configured such that it has an engaging end that is convex and is more preferably spherical so that when engaged by a cylindrical cutter the cutter can self center on the engaging end. The cutter is also preferably spring biased which provides increased pressure for engaging the anvil. The vessel wall is distended over the anvil which enables the wall to be stretched. This assists in creating a clean cut.
The ability to distend the vessel wall is particularly useful when a compression plate apparatus is utilized to join the vessels. This compression plate apparatus includes two opposing and generally annular compression plates in a generally coaxial orientation. The end of the graft vessel that is to be anastomosed is everted onto one of the compression plates. The anvil pull is used to distend the receiving vessel wall such that it extends into a compression plate apparatus. With the other compression plate placed at and around the anastomosis site, an anastomosis fenestra is opened in the wall of the receiving vessel. This anastomosis fenestra is opened within the annular region generally defined by the compression plate located at and around the anastomosis site. With the aid of the anvil of this invention, the contour of the anastomosed fenestra is engaged with the compression plate which opposes the compression plate that carries the graft vessel. This engagement is preferably accomplished with the aid of holding tabs or other similar features protruding from the compression plate placed around the anastomosis fenestra.
The degree to which the anvil has distended the receiving vessel before formation of the fenestra determines the size of the portion defining the vessel opening that remains in the compression plate apparatus. By adequately distending the receiving vessel wall, the portion defining the opening can be captured by the compression plate apparatus and everted. The graft vessel is subsequently approached to the anastomosis fenestra by reducing the separation between the compression plates, so that the graft vessel causes the eversion of the contour of the anastomosis fenestra by appropriately sliding on the surface of the anvil. Once the portion of the vessel that defines the opening has been everted then the compression plate apparatus can be compressed in a manner such that the everted portion of the receiving vessel is held against the everted portion of the other vessel such as a graft vessel. The relative separation of the compression plates is reduced to the extent necessary to bring the everted edges of the anastomosed structures into contact engagement so that a leak proof anastomosis is achieved.
A feature of the present invention is that the anvil is configured in a way such that it cooperates with the cutting element in the opening of the anastomosis fenestra in the target vessel and it also cooperates with the compression plate apparatus in the eversion of the edge of the target vessel at the anastomosed fenestra. By joining the everted contour of the target vessel at the anastomosis fenestra with the everted edge of the graft vessel, significant exposure to the blood flow of the cut portion of the anastomosed structures is avoided. Furthermore, the use of the anvil in a plurality of operations permits a considerable simplification of the anastomosis procedure. These operations include the abutting of the receiving blood vessel wall at the anastomosis site, the opening of the anastomosis fenestra in the receiving blood vessel, the eversion of the edge of the target vessel at the anastomosis fenestra, and the joining of the anastomosed structures.
An external anastomosis operator is also provided that controls the anastomosis procedure once the anvil pull extends out of the wall of the vessel and can be engaged. The external anastomosis operator enables the anastomosis procedure to be mechanized so that it is rapidly and reliably completed in a highly controlled manner.
By not requiring the interruption of blood flow in the receiving blood vessel, the active endoscopic or peripheral procedure of this invention advantageously reduces or even eliminates the risk of ischemia in organs that receive their main supply of blood through the receiving blood vessel. Furthermore, the exposure of the anastomosis area is reduced because no devices have to be introduced to temporarily interrupt blood flow. This feature advantageously enhances the minimally invasive character of the methods, systems, and apparatuses of this invention and the intervention time for the practice of the anastomosis.
Additional aspects and advantages of this invention will be apparent from the following detailed description of preferred embodiments thereof, which proceeds with reference to the accompanying drawings.